1. Field of the Invention
The present invention relates to a photosensor and particularly to a framing of a photosensor.
2. Description of the Prior Art
A photosensor in which a photoelectric conversion device in the form of a film is provided on a transparent support substrate is disclosed for example in Japanese Patent Laying-Open Gazette No. 31585/1983. This photoelectric conversion device requires a support substrate since it is formed as a film. A transparent substrate of a plate such as glass or plastic can be provided on a front face of a photoelectric conversion device on which light is incident, whereby the front face of the photoelectric conversion device can be protected. It is found that light is introduced to such a photoelectric conversion device not only through a major surface of the substrate but also through narrow lateral faces parallel to the direction of the thickness thereof. In consequence, in order to intercept light on the lateral faces of the substrate, a protection film of colored resin for protection of the back face of the photoelectric conversion device extends to also cover the lateral faces of the substrate.
However, it is difficult to automatically effect work for covering the lateral faces of the substrate when the protection film and coating work has to be done manually in such a conventional device.
On the other hand, in a molding method using dyes, at least a front face of a substrate on which light is incident needs to be selectively exposed and accordingly a manufacturing process is complicated and not practical.
A photosensor having an optical filter for cutting off light in a specified wavelength region such as an infrared (IR) region on a front face of a photoelectric conversion device is disclosed for example in Japanese Patent Laying-Open Gazette No. 197783/1983. In the photosensor disclosed in this Gazette, the photoelectric conversion device is formed by using single crystal silicon whose spectrum sensitivity region covers not only a visible region but also the infrared region, and accordingly an IR cut-off filter is needed if only light in the visible region is to be measured.
On the other hand, the above mentioned Japanese Patent Laying-Open Gazette No. 31585/1983 discloses a photosensor having a photoelectric conversion device using amorphous silicon whose spectral sensitivity region almost coincides with the visible region as shown in FIG. 5. In addition, a color sensor in which blue, green and red color filters are disposed on a front face of a photoelectric conversion device using amorphous silicon is disclosed in Japanese Patent Laying-Open Gazette No. 148372/1984. In such a photoelectric conversion device using amorphous silicon, a spectral sensitivity region almost coincides with the visible region as described above. However, boundary regions of the spectral sensitivity region slightly extend into the infrared (IR) region or an ultraviolet (UV) region and accordingly, in order to measure light only in the visible region with precision, an IR cut-off filter and a UV cut-off filter are required.
If such an optical cut-off filter is fixed by an adhesive agent on a light admitting face of a support substrate directly or through a color filter, the cut-off filter is sometimes detached or broken in a heat cycle test or a humidity test. Consequently, such conventional sensors have little reliability and cannot be practically utilized.